A conventional chair or sofa typically comprises a rectangular frame or “seat box” having a having at least one cushion supported over a plurality of elongated springs stretched between the sides of the seat box. Another common configuration, particularly in sofas, is stretching a downwardly deflectable wire webbing between the sides of the seat box. The wire webbing frequently comprises interlinked wire, coiled springs or s-shaped springs, collectively referred to as the “seat springs.” The springs are typically stretched across the frame of the seat box to provide a flexible, yet supportive seating surface in which the seat springs stretch axially in response to weight applied transversely from a sitting individual being such that the seating surface flexes downward to provide a contoured and more comfortable seat. The springs are typically mounted to the frame such that the springs initially under tension maintaining at level surface until a person sits on the seat cushions. The pre-tensioned springs also bias the seat surface back to a level surface after a seated person stands up. The frame is often assembled prior to the springs being attached to provide the structural support for tensioning the springs. The inherent drawback of pre-assembling the frame is that the large frames used for sofas and other seating furniture can be difficult to maneuver and position for attachment of the springs making assembly tedious and labor intensive.
The springs stretch to provide a contoured seating surface for individuals seated on the sofa until the downward weight of the seated person equalizes with the force required to continue stretching the springs, thereby stopping the downward decent of the seated person. In order to accommodate the weight of a wide range of possible weights, including people weighing several hundred pounds, without breaking, the springs typically have high tensile strength requiring substantial axial force to stretch. The significant tensile strength required to tension the springs individually can be labor intensive requiring repeated application of significant physical exertion to stretch and attach each spring. In addition, the strength required to stretch all the springs at once is often too much for single individual requiring the springs to be attached individually or in small groups. An obvious manufacturing concern is always minimizing the amount of labor and time of construction in manufacturing furniture. In the arena of mass marketed furniture, the improving assembly time by even a minimal amount can result in cost savings. The tedious and tiring process of stretching and attaching the springs can create a substantial bottleneck in the manufacturing process, particular as workers continue to tire from manually stretching the springs.
Known spring stretchers can reduce fatigue in the assembler, but can be equally if not more time consuming than manually assembling the springs. Although handheld mechanical springs stretchers can make stretching and maintaining the springs in the stretched position easier, affixing the springs to the seat box while attached the handheld stretcher and then removing the stretcher can be even more tedious and time consuming.
The inherent manufacturing challenge of tensioning and installing high tensile springs on the seat box of a furniture item creates a need for a means of efficiently attaching tensile springs in furniture assembly.